Transformation of Dion-Jacobson phase to Aurivillius phase: synthesis of (PbBiO2)MNb2O7 (MÂ =Â La, Bi)

We describe transformations of the Dion-Jacobson (D-J) phases, KLaNb2O7 and RbBiNb2O7, to the Aurivillius (A) phases, (PbBiO2)LaNb2O7 (1) and (PbBiO2)BiNb2O7 (2), in a metathesis reaction with PbBiO2Cl. Oxide 1 adopts centrosymmetric tetragonal structure (a = 3.905(1) Å, c = 25.66(1) Å), whereas oxide 2 crystallizes in a noncentrosymmetric orthorhombic (A21am) (a = 5.489(1) Å, b = 5.496(2) Å, c = 25.53(1) Å) structure. Oxide 2 shows a distinct SHG response towards 1064 nm laser radiation. The role of La3+ versus Bi3+ in the perovskite slabs for the occurrence of noncentrosymmetric structure/ferroic property in these materials is pointed out.